1
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Li P, Chen P, Qi F, Shi J, Zhu W, Li J, Zhang P, Xie H, Li L, Lei M, Ren X, Wang W, Zhang L, Xiang X, Zhang Y, Gao Z, Feng X, Du W, Liu X, Xia L, Liu BF, Li Y. High-throughput and proteome-wide discovery of endogenous biomolecular condensates. Nat Chem 2024; 16:1101-1112. [PMID: 38499848 DOI: 10.1038/s41557-024-01485-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 02/23/2024] [Indexed: 03/20/2024]
Abstract
Phase separation inside mammalian cells regulates the formation of the biomolecular condensates that are related to gene expression, signalling, development and disease. However, a large population of endogenous condensates and their candidate phase-separating proteins have yet to be discovered in a quantitative and high-throughput manner. Here we demonstrate that endogenously expressed biomolecular condensates can be identified across a cell's proteome by sorting proteins across varying oligomeric states. We employ volumetric compression to modulate the concentrations of intracellular proteins and the degree of crowdedness, which are physical regulators of cellular biomolecular condensates. The changes in degree of the partition of proteins into condensates or phase separation led to varying oligomeric states of the proteins, which can be detected by coupling density gradient ultracentrifugation and quantitative mass spectrometry. In total, we identified 1,518 endogenous condensate proteins, of which 538 have not been reported before. Furthermore, we demonstrate that our strategy can identify condensate proteins that respond to specific biological processes.
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Affiliation(s)
- Pengjie Li
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Peng Chen
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Fukang Qi
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Jinyun Shi
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Wenjie Zhu
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Jiashuo Li
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Peng Zhang
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Han Xie
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Lina Li
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Mengcheng Lei
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Xueqing Ren
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Wenhui Wang
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Liang Zhang
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Xufu Xiang
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Yiwei Zhang
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Zhaolong Gao
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Xiaojun Feng
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Wei Du
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Xin Liu
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Limin Xia
- Department of Gastroenterology, Hubei Key Laboratory of Hepato-Pancreato-Biliary Diseases, Institute of Liver and Gastrointestinal Diseases, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Bi-Feng Liu
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China.
| | - Yiwei Li
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China.
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2
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Bernard C, Exposito-Alonso D, Selten M, Sanalidou S, Hanusz-Godoy A, Aguilera A, Hamid F, Oozeer F, Maeso P, Allison L, Russell M, Fleck RA, Rico B, Marín O. Cortical wiring by synapse type-specific control of local protein synthesis. Science 2022; 378:eabm7466. [PMID: 36423280 DOI: 10.1126/science.abm7466] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
Neurons use local protein synthesis to support their morphological complexity, which requires independent control across multiple subcellular compartments up to the level of individual synapses. We identify a signaling pathway that regulates the local synthesis of proteins required to form excitatory synapses on parvalbumin-expressing (PV+) interneurons in the mouse cerebral cortex. This process involves regulation of the TSC subunit 2 (Tsc2) by the Erb-B2 receptor tyrosine kinase 4 (ErbB4), which enables local control of messenger RNA {mRNA} translation in a cell type-specific and synapse type-specific manner. Ribosome-associated mRNA profiling reveals a molecular program of synaptic proteins downstream of ErbB4 signaling required to form excitatory inputs on PV+ interneurons. Thus, specific connections use local protein synthesis to control synapse formation in the nervous system.
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Affiliation(s)
- Clémence Bernard
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - David Exposito-Alonso
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Martijn Selten
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Stella Sanalidou
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Alicia Hanusz-Godoy
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Alfonso Aguilera
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Fursham Hamid
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Fazal Oozeer
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Patricia Maeso
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Leanne Allison
- Centre for Ultrastructural Imaging, King's College London, London SE1 1UL, UK
| | - Matthew Russell
- Centre for Ultrastructural Imaging, King's College London, London SE1 1UL, UK
| | - Roland A Fleck
- Centre for Ultrastructural Imaging, King's College London, London SE1 1UL, UK
| | - Beatriz Rico
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Oscar Marín
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
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3
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EPHA2 biallelic disruption causes syndromic complex microphthalmia with iris hypoplasia. Eur J Med Genet 2022; 65:104574. [DOI: 10.1016/j.ejmg.2022.104574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 06/26/2022] [Accepted: 07/20/2022] [Indexed: 11/23/2022]
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4
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Engmann AK, Hatch JJ, Nanda P, Veeraraghavan P, Ozkan A, Poulopoulos A, Murphy AJ, Macklis JD. Neuronal subtype-specific growth cone and soma purification from mammalian CNS via fractionation and fluorescent sorting for subcellular analyses and spatial mapping of local transcriptomes and proteomes. Nat Protoc 2022; 17:222-251. [PMID: 35022617 PMCID: PMC9751848 DOI: 10.1038/s41596-021-00638-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 09/24/2021] [Indexed: 11/09/2022]
Abstract
During neuronal development, growth cones (GCs) of projection neurons navigate complex extracellular environments to reach distant targets, thereby generating extraordinarily complex circuitry. These dynamic structures located at the tips of axonal projections respond to substrate-bound as well as diffusible guidance cues in a neuronal subtype- and stage-specific manner to construct highly specific and functional circuitry. In vitro studies of the past decade indicate that subcellular localization of specific molecular machinery in GCs underlies the precise navigational control that occurs during circuit 'wiring'. Our laboratory has recently developed integrated experimental and analytical approaches enabling high-depth, quantitative proteomic and transcriptomic investigation of subtype- and stage-specific GC molecular machinery directly from the rodent central nervous system (CNS) in vivo. By using these approaches, a pure population of GCs and paired somata can be isolated from any neuronal subtype of the CNS that can be fluorescently labeled. GCs are dissociated from parent axons using fluid shear forces, and a bulk GC fraction is isolated by buoyancy ultracentrifugation. Subtype-specific GCs and somata are purified by recently developed fluorescent small particle sorting and established FACS of neurons and are suitable for downstream analyses of proteins and RNAs, including small RNAs. The isolation of subtype-specific GCs and parent somata takes ~3 h, plus sorting time, and ~1-2 h for subsequent extraction of molecular contents. RNA library preparation and sequencing can take several days to weeks, depending on the turnaround time of the core facility involved.
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Affiliation(s)
- Anne K Engmann
- Department of Stem Cell and Regenerative Biology and Center for Brain Science, Harvard University, Cambridge, MA, USA
| | - John J Hatch
- Department of Stem Cell and Regenerative Biology and Center for Brain Science, Harvard University, Cambridge, MA, USA
| | - Prakruti Nanda
- Department of Stem Cell and Regenerative Biology and Center for Brain Science, Harvard University, Cambridge, MA, USA
| | - Priya Veeraraghavan
- Department of Stem Cell and Regenerative Biology and Center for Brain Science, Harvard University, Cambridge, MA, USA
| | - Abdulkadir Ozkan
- Department of Stem Cell and Regenerative Biology and Center for Brain Science, Harvard University, Cambridge, MA, USA
| | - Alexandros Poulopoulos
- Department of Stem Cell and Regenerative Biology and Center for Brain Science, Harvard University, Cambridge, MA, USA
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Alexander J Murphy
- Department of Stem Cell and Regenerative Biology and Center for Brain Science, Harvard University, Cambridge, MA, USA
- Takeda Pharmaceutical Company Limited, Cambridge, MA, USA
| | - Jeffrey D Macklis
- Department of Stem Cell and Regenerative Biology and Center for Brain Science, Harvard University, Cambridge, MA, USA.
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5
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Koppers M, Holt CE. Receptor-Ribosome Coupling: A Link Between Extrinsic Signals and mRNA Translation in Neuronal Compartments. Annu Rev Neurosci 2022; 45:41-61. [DOI: 10.1146/annurev-neuro-083021-110015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Axons receive extracellular signals that help to guide growth and synapse formation during development and to maintain neuronal function and survival during maturity. These signals relay information via cell surface receptors that can initiate local intracellular signaling at the site of binding, including local messenger RNA (mRNA) translation. Direct coupling of translational machinery to receptors provides an attractive way to activate this local mRNA translation and change the local proteome with high spatiotemporal resolution. Here, we first discuss the increasing evidence that different external stimuli trigger translation of specific subsets of mRNAs in axons via receptors and thus play a prominent role in various processes in both developing and mature neurons. We then discuss the receptor-mediated molecular mechanisms that regulate local mRNA translational with a focus on direct receptor-ribosome coupling. We advance the idea that receptor-ribosome coupling provides several advantages over other translational regulation mechanisms and is a common mechanism in cell communication. Expected final online publication date for the Annual Review of Neuroscience, Volume 45 is July 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Max Koppers
- Department of Biology, Division of Cell Biology, Neurobiology and Biophysics, Utrecht University, Utrecht, The Netherlands
| | - Christine E. Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
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6
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Jones JI, Costa CJ, Cooney C, Goldberg DC, Ponticiello M, Cohen MW, Mellado W, Ma TC, Willis DE. Failure to Upregulate the RNA Binding Protein ZBP After Injury Leads to Impaired Regeneration in a Rodent Model of Diabetic Peripheral Neuropathy. Front Mol Neurosci 2021; 14:728163. [PMID: 34949989 PMCID: PMC8688773 DOI: 10.3389/fnmol.2021.728163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 11/16/2021] [Indexed: 12/03/2022] Open
Abstract
Most diabetes patients eventually suffer from peripheral nerve degeneration. Unfortunately, there is no treatment for the condition and its mechanisms are not well understood. There is, however, an emerging consensus that the inability of peripheral nerves to regenerate normally after injury contributes to the pathophysiology. We have previously shown that regeneration of peripheral axons requires local axonal translation of a pool of axonal mRNAs and that the levels and members of this axonal mRNA pool are altered in response to injury. Here, we show that following sciatic nerve injury in a streptozotocin rodent model of type I diabetes, this mobilization of RNAs into the injured axons is attenuated and correlates with decreased axonal regeneration. This failure of axonal RNA localization results from decreased levels of the RNA binding protein ZBP1. Over-expression of ZBP1 rescues the in vitro growth defect in injured dorsal root ganglion neurons from diabetic rodents. These results provide evidence that decreased neuronal responsiveness to injury in diabetes is due to a decreased ability to alter the pool of axonal mRNAs available for local translation, and may open new therapeutic opportunities for diabetic peripheral neuropathy.
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Affiliation(s)
- James I Jones
- Burke Neurological Institute, White Plains, NY, United States
| | | | - Caitlin Cooney
- Burke Neurological Institute, White Plains, NY, United States
| | | | | | - Melanie W Cohen
- Burke Neurological Institute, White Plains, NY, United States
| | | | - Thong C Ma
- Burke Neurological Institute, White Plains, NY, United States.,Feil Family Brain & Mind Research Institute, Weill Cornell Medicine, New York, NY, United States
| | - Dianna E Willis
- Burke Neurological Institute, White Plains, NY, United States.,Feil Family Brain & Mind Research Institute, Weill Cornell Medicine, New York, NY, United States
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7
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Li L, Yu J, Ji SJ. Axonal mRNA localization and translation: local events with broad roles. Cell Mol Life Sci 2021; 78:7379-7395. [PMID: 34698881 PMCID: PMC11072051 DOI: 10.1007/s00018-021-03995-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 09/17/2021] [Accepted: 10/14/2021] [Indexed: 12/19/2022]
Abstract
Messenger RNA (mRNA) can be transported and targeted to different subcellular compartments and locally translated. Local translation is an evolutionally conserved mechanism that in mammals, provides an important tool to exquisitely regulate the subcellular proteome in different cell types, including neurons. Local translation in axons is involved in processes such as neuronal development, function, plasticity, and diseases. Here, we summarize the current progress on axonal mRNA transport and translation. We focus on the regulatory mechanisms governing how mRNAs are transported to axons and how they are locally translated in axons. We discuss the roles of axonally synthesized proteins, which either function locally in axons, or are retrogradely trafficked back to soma to achieve neuron-wide gene regulation. We also examine local translation in neurological diseases. Finally, we give a critical perspective on the remaining questions that could be answered to uncover the fundamental rules governing local translation, and discuss how this could lead to new therapeutic targets for neurological diseases.
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Affiliation(s)
- Lichao Li
- School of Life Sciences, Department of Biology, Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, Guangdong, China
| | - Jun Yu
- School of Life Sciences, Department of Biology, Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, Guangdong, China
| | - Sheng-Jian Ji
- School of Life Sciences, Department of Biology, Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Brain Research Center, Southern University of Science and Technology, Shenzhen, 518055, Guangdong, China.
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8
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Dalla Costa I, Buchanan CN, Zdradzinski MD, Sahoo PK, Smith TP, Thames E, Kar AN, Twiss JL. The functional organization of axonal mRNA transport and translation. Nat Rev Neurosci 2021; 22:77-91. [PMID: 33288912 PMCID: PMC8161363 DOI: 10.1038/s41583-020-00407-7] [Citation(s) in RCA: 86] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/26/2020] [Indexed: 12/13/2022]
Abstract
Axons extend for tremendously long distances from the neuronal soma and make use of localized mRNA translation to rapidly respond to different extracellular stimuli and physiological states. The locally synthesized proteins support many different functions in both developing and mature axons, raising questions about the mechanisms by which local translation is organized to ensure the appropriate responses to specific stimuli. Publications over the past few years have uncovered new mechanisms for regulating the axonal transport and localized translation of mRNAs, with several of these pathways converging on the regulation of cohorts of functionally related mRNAs - known as RNA regulons - that drive axon growth, axon guidance, injury responses, axon survival and even axonal mitochondrial function. Recent advances point to these different regulatory pathways as organizing platforms that allow the axon's proteome to be modulated to meet its physiological needs.
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Affiliation(s)
- Irene Dalla Costa
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Courtney N Buchanan
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | | | - Pabitra K Sahoo
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Terika P Smith
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Elizabeth Thames
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Amar N Kar
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Jeffery L Twiss
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA.
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9
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D’Arcy BR, Silver DL. Local gene regulation in radial glia: Lessons from across the nervous system. Traffic 2020; 21:737-748. [PMID: 33058331 PMCID: PMC7723028 DOI: 10.1111/tra.12769] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 09/16/2020] [Accepted: 10/12/2020] [Indexed: 01/15/2023]
Abstract
Radial glial cells (RGCs) are progenitors of the cerebral cortex which produce both neurons and glia during development. Given their central role in development, RGC dysfunction can result in diverse neurodevelopmental disorders. RGCs have an elongated bipolar morphology that spans the entire radial width of the cortex and ends in basal endfeet connected to the pia. The basal process and endfeet are important for proper guidance of migrating neurons and are implicated in signaling. However, endfeet must function at a great distance from the cell body. This spatial separation suggests a role for local gene regulation in endfeet. Endfeet contain a local transcriptome enriched for cytoskeletal and signaling factors. These localized mRNAs are actively transported from the cell body and can be locally translated in endfeet. Yet, studies of local gene regulation in RGC endfeet are still in their infancy. Here, we draw comparisons of RGCs with foundational work in anatomically and phylogenetically related cell types, neurons and astrocytes. Our review highlights a striking overlap in the types of RNAs localized, as well as principles of local translation between these three cell types. Thus, studies in neurons, astrocytes and RGCs can mutually inform an understanding of RNA localization across the nervous system.
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Affiliation(s)
- Brooke R. D’Arcy
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina
| | - Debra L. Silver
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina
- Department of Neurobiology, Duke University Medical Center, Durham, North Carolina
- Duke Institute for Brain Sciences, Duke University Medical Center, Durham, North Carolina
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10
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Alvarez S, Varadarajan SG, Butler SJ. Dorsal commissural axon guidance in the developing spinal cord. Curr Top Dev Biol 2020; 142:197-231. [PMID: 33706918 DOI: 10.1016/bs.ctdb.2020.10.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Commissural axons have been a key model system for identifying axon guidance signals in vertebrates. This review summarizes the current thinking about the molecular and cellular mechanisms that establish a specific commissural neural circuit: the dI1 neurons in the developing spinal cord. We assess the contribution of long- and short-range signaling while sequentially following the developmental timeline from the birth of dI1 neurons, to the extension of commissural axons first circumferentially and then contralaterally into the ventral funiculus.
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Affiliation(s)
- Sandy Alvarez
- Department of Neurobiology, University of California, Los Angeles, CA, United States; Molecular Biology Interdepartmental Doctoral Program, University of California, Los Angeles, CA, United States
| | | | - Samantha J Butler
- Department of Neurobiology, University of California, Los Angeles, CA, United States; Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, CA, United States.
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11
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Corradi E, Baudet ML. In the Right Place at the Right Time: miRNAs as Key Regulators in Developing Axons. Int J Mol Sci 2020; 21:ijms21228726. [PMID: 33218218 PMCID: PMC7699167 DOI: 10.3390/ijms21228726] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/12/2020] [Accepted: 11/16/2020] [Indexed: 01/02/2023] Open
Abstract
During neuronal circuit formation, axons progressively develop into a presynaptic compartment aided by extracellular signals. Axons display a remarkably high degree of autonomy supported in part by a local translation machinery that permits the subcellular production of proteins required for their development. Here, we review the latest findings showing that microRNAs (miRNAs) are critical regulators of this machinery, orchestrating the spatiotemporal regulation of local translation in response to cues. We first survey the current efforts toward unraveling the axonal miRNA repertoire through miRNA profiling, and we reveal the presence of a putative axonal miRNA signature. We also provide an overview of the molecular underpinnings of miRNA action. Our review of the available experimental evidence delineates two broad paradigms: cue-induced relief of miRNA-mediated inhibition, leading to bursts of protein translation, and cue-induced miRNA activation, which results in reduced protein production. Overall, this review highlights how a decade of intense investigation has led to a new appreciation of miRNAs as key elements of the local translation regulatory network controlling axon development.
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12
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Guillaud L, El-Agamy SE, Otsuki M, Terenzio M. Anterograde Axonal Transport in Neuronal Homeostasis and Disease. Front Mol Neurosci 2020; 13:556175. [PMID: 33071754 PMCID: PMC7531239 DOI: 10.3389/fnmol.2020.556175] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 08/26/2020] [Indexed: 12/12/2022] Open
Abstract
Neurons are highly polarized cells with an elongated axon that extends far away from the cell body. To maintain their homeostasis, neurons rely extensively on axonal transport of membranous organelles and other molecular complexes. Axonal transport allows for spatio-temporal activation and modulation of numerous molecular cascades, thus playing a central role in the establishment of neuronal polarity, axonal growth and stabilization, and synapses formation. Anterograde and retrograde axonal transport are supported by various molecular motors, such as kinesins and dynein, and a complex microtubule network. In this review article, we will primarily discuss the molecular mechanisms underlying anterograde axonal transport and its role in neuronal development and maturation, including the establishment of functional synaptic connections. We will then provide an overview of the molecular and cellular perturbations that affect axonal transport and are often associated with axonal degeneration. Lastly, we will relate our current understanding of the role of axonal trafficking concerning anterograde trafficking of mRNA and its involvement in the maintenance of the axonal compartment and disease.
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Affiliation(s)
- Laurent Guillaud
- Molecular Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Sara Emad El-Agamy
- Molecular Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Miki Otsuki
- Molecular Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Marco Terenzio
- Molecular Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
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13
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Quantification of mRNA translation in live cells using single-molecule imaging. Nat Protoc 2020; 15:1371-1398. [PMID: 32076351 DOI: 10.1038/s41596-019-0284-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 12/13/2019] [Indexed: 11/09/2022]
Abstract
mRNA translation is a key step in gene expression. Proper regulation of translation efficiency ensures correct protein expression levels in the cell, which is essential to cell function. Different methods used to study translational control in the cell rely on population-based assays that do not provide information about translational heterogeneity between cells or between mRNAs of the same gene within a cell, and generally provide only a snapshot of translation. To study translational heterogeneity and measure translation dynamics, we have developed microscopy-based methods that enable visualization of translation of single mRNAs in live cells. These methods consist of a set of genetic tools, an imaging-based approach and sophisticated computational tools. Using the translation imaging method, one can investigate many new aspects of translation in single living cells, such as translation start-site selection, 3'-UTR (untranslated region) translation and translation-coupled mRNA decay. Here, we describe in detail how to perform such experiments, including reporter design, cell line generation, image acquisition and analysis. This protocol also provides a detailed description of the image analysis pipeline and computational modeling that will enable non-experts to correctly interpret fluorescence measurements. The protocol takes 2-4 d to complete (after cell lines expressing all required transgenes have been generated).
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14
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Farias J, Sotelo JR, Sotelo‐Silveira J. Toward Axonal System Biology: Genome Wide Views of Local mRNA Translation. Proteomics 2019; 19:e1900054. [DOI: 10.1002/pmic.201900054] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 04/12/2019] [Indexed: 11/10/2022]
Affiliation(s)
- Joaquina Farias
- Departamento de Proteínas y Ácidos NucleicosInstituto de Investigaciones Biológicas Clemente Estable Montevideo CP 11600 Uruguay
- Departamento de GenómicaInstituto de Investigaciones Biológicas Clemente Estable Montevideo CP 11600 Uruguay
| | - José Roberto Sotelo
- Departamento de Proteínas y Ácidos NucleicosInstituto de Investigaciones Biológicas Clemente Estable Montevideo CP 11600 Uruguay
| | - José Sotelo‐Silveira
- Departamento de GenómicaInstituto de Investigaciones Biológicas Clemente Estable Montevideo CP 11600 Uruguay
- Sección Biología CelularFacultad de Ciencias, Universidad de la República Montevideo CP 11400 Uruguay
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15
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de la Peña JBI, Song JJ, Campbell ZT. RNA control in pain: Blame it on the messenger. WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 10:e1546. [PMID: 31090211 DOI: 10.1002/wrna.1546] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 04/17/2019] [Accepted: 04/22/2019] [Indexed: 12/12/2022]
Abstract
mRNA function is meticulously controlled. We provide an overview of the integral role that posttranscriptional controls play in the perception of painful stimuli by sensory neurons. These specialized cells, termed nociceptors, precisely regulate mRNA polarity, translation, and stability. A growing body of evidence has revealed that targeted disruption of mRNAs and RNA-binding proteins robustly diminishes pain-associated behaviors. We propose that the use of multiple independent regulatory paradigms facilitates robust temporal and spatial precision of protein expression in response to a range of pain-promoting stimuli. This article is categorized under: RNA in Disease and Development > RNA in Disease Translation > Translation Regulation RNA Turnover and Surveillance > Regulation of RNA Stability.
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Affiliation(s)
- June Bryan I de la Peña
- Department of Biological Sciences and the Center for Advanced Pain Studies, University of Texas, Dallas, Richardson, Texas
| | - Jane J Song
- Department of Biological Sciences and the Center for Advanced Pain Studies, University of Texas, Dallas, Richardson, Texas
| | - Zachary T Campbell
- Department of Biological Sciences and the Center for Advanced Pain Studies, University of Texas, Dallas, Richardson, Texas
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16
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Chen YC, Chang YW, Huang YS. Dysregulated Translation in Neurodevelopmental Disorders: An Overview of Autism-Risk Genes Involved in Translation. Dev Neurobiol 2018; 79:60-74. [PMID: 30430754 DOI: 10.1002/dneu.22653] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 09/17/2018] [Accepted: 10/25/2018] [Indexed: 01/08/2023]
Abstract
Regulated local translation-whereby specific mRNAs are transported and localized in subcellular domains where they are translated in response to regional signals-allows for remote control of gene expression to concentrate proteins in subcellular compartments. Neurons are highly polarized cells with unique features favoring local control for axonal pathfinding and synaptic plasticity, which are key processes involved in constructing functional circuits in the developing brain. Neurodevelopmental disorders are caused by genetic or environmental factors that disturb the nervous system's development during prenatal and early childhood periods. The growing list of genetic mutations that affect mRNA translation raises the question of whether aberrant translatomes in individuals with neurodevelopmental disorders share common molecular features underlying their stereotypical phenotypes and, vice versa, cause a certain degree of phenotypic heterogeneity. Here, we briefly give an overview of the role of local translation during neuronal development. We take the autism-risk gene list and discuss the molecules that (perhaps) are involved in mRNA transport and translation. Both exaggerated and suppressed translation caused by mutations in those genes have been identified or suggested. Finally, we discuss some proof-of-principle regimens for use in autism mouse models to correct dysregulated translation.
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Affiliation(s)
- Yan-Chu Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Yu-Wei Chang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Yi-Shuian Huang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, 11529, Taiwan
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17
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Abstract
During nervous system development, neurons extend axons to reach their targets and form functional circuits. The faulty assembly or disintegration of such circuits results in disorders of the nervous system. Thus, understanding the molecular mechanisms that guide axons and lead to neural circuit formation is of interest not only to developmental neuroscientists but also for a better comprehension of neural disorders. Recent studies have demonstrated how crosstalk between different families of guidance receptors can regulate axonal navigation at choice points, and how changes in growth cone behaviour at intermediate targets require changes in the surface expression of receptors. These changes can be achieved by a variety of mechanisms, including transcription, translation, protein-protein interactions, and the specific trafficking of proteins and mRNAs. Here, I review these axon guidance mechanisms, highlighting the most recent advances in the field that challenge the textbook model of axon guidance.
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Affiliation(s)
- Esther T Stoeckli
- University of Zurich, Institute of Molecular Life Sciences, Neuroscience Center Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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18
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Palladin Is a Neuron-Specific Translational Target of mTOR Signaling That Regulates Axon Morphogenesis. J Neurosci 2018; 38:4985-4995. [PMID: 29712777 DOI: 10.1523/jneurosci.2370-17.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 04/09/2018] [Accepted: 04/14/2018] [Indexed: 11/21/2022] Open
Abstract
The mTOR signaling pathway regulates protein synthesis and diverse aspects of neuronal morphology that are important for brain development and function. To identify proteins controlled translationally by mTOR signaling, we performed ribosome profiling analyses in mouse cortical neurons and embryonic stem cells upon acute mTOR inhibition. Among proteins whose translation was significantly affected by mTOR inhibition selectively in neurons, we identified the cytoskeletal regulator protein palladin, which is localized within the cell body and axons in hippocampal neurons. Knockdown of palladin eliminated supernumerary axons induced by suppression of the tuberous sclerosis complex protein TSC1 in neurons, demonstrating that palladin regulates neuronal morphogenesis downstream of mTOR signaling. Our findings provide novel insights into an mTOR-dependent mechanism that controls neuronal morphogenesis through translational regulation.SIGNIFICANCE STATEMENT This study reports the discovery of neuron-specific protein translational responses to alterations of mTOR activity. By using ribosome profiling analysis, which can reveal the location and quantity of translating ribosomes on mRNAs, multiple aspects of protein translation were quantitatively analyzed in mouse embryonic stem cells and cortical neurons upon acute mTOR inhibition. Neurons displayed distinct patterns of ribosome occupancy for each codon and ribosome stalling during translation at specific positions of mRNAs. Importantly, the cytoskeletal regulator palladin was identified as a translational target protein of mTOR signaling in neurons. Palladin operates downstream of mTOR to modulate axon morphogenesis. This study identifies a novel mechanism of neuronal morphogenesis regulated by mTOR signaling through control of translation of the key protein palladin.
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19
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Sahoo PK, Smith DS, Perrone-Bizzozero N, Twiss JL. Axonal mRNA transport and translation at a glance. J Cell Sci 2018; 131:jcs196808. [PMID: 29654160 PMCID: PMC6518334 DOI: 10.1242/jcs.196808] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Localization and translation of mRNAs within different subcellular domains provides an important mechanism to spatially and temporally introduce new proteins in polarized cells. Neurons make use of this localized protein synthesis during initial growth, regeneration and functional maintenance of their axons. Although the first evidence for protein synthesis in axons dates back to 1960s, improved methodologies, including the ability to isolate axons to purity, highly sensitive RNA detection methods and imaging approaches, have shed new light on the complexity of the transcriptome of the axon and how it is regulated. Moreover, these efforts are now uncovering new roles for locally synthesized proteins in neurological diseases and injury responses. In this Cell Science at a Glance article and the accompanying poster, we provide an overview of how axonal mRNA transport and translation are regulated, and discuss their emerging links to neurological disorders and neural repair.
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Affiliation(s)
- Pabitra K Sahoo
- Department of Biological Sciences, University of South Carolina, 715 Sumter St., CLS 401, Columbia, SC 29208, USA
| | - Deanna S Smith
- Department of Biological Sciences, University of South Carolina, 715 Sumter St., CLS 401, Columbia, SC 29208, USA
| | - Nora Perrone-Bizzozero
- Department of Neurosciences, University of New Mexico School of Medicine, 1 University of New Mexico, MSC08 4740, Albuquerque, NM 87131, USA
| | - Jeffery L Twiss
- Department of Biological Sciences, University of South Carolina, 715 Sumter St., CLS 401, Columbia, SC 29208, USA
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20
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Chuang CF, King CE, Ho BW, Chien KY, Chang YC. Unbiased Proteomic Study of the Axons of Cultured Rat Cortical Neurons. J Proteome Res 2018; 17:1953-1966. [DOI: 10.1021/acs.jproteome.8b00069] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
| | | | | | - Kun-Yi Chien
- Department of Biochemistry and Molecular Biology, College of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan
- Clinical Proteomics Core Laboratory, Linkou Chang Gung Memorial Hospital, Taoyuan City 33305, Taiwan
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21
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González C, Cornejo VH, Couve A. Golgi bypass for local delivery of axonal proteins, fact or fiction? Curr Opin Cell Biol 2018; 53:9-14. [PMID: 29631154 DOI: 10.1016/j.ceb.2018.03.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 03/26/2018] [Accepted: 03/29/2018] [Indexed: 02/07/2023]
Abstract
Although translation of cytosolic proteins is well described in axons, much less is known about the synthesis, processing and trafficking of transmembrane and secreted proteins. A canonical rough endoplasmic reticulum or a stacked Golgi apparatus has not been detected in axons, generating doubts about the functionality of a local route. However, axons contain mRNAs for membrane and secreted proteins, translation factors, ribosomal components, smooth endoplasmic reticulum and post-endoplasmic reticulum elements that may contribute to local biosynthesis and plasma membrane delivery. Here we consider the evidence supporting a local secretory system in axons. We discuss exocytic elements and examples of autonomous axonal trafficking that impact development and maintenance. We also examine whether unconventional post-endoplasmic reticulum pathways may replace the canonical Golgi apparatus.
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Affiliation(s)
- Carolina González
- Department of Neuroscience, Facultad de Medicina, Universidad de Chile, Chile; Biomedical Neuroscience Institute (BNI), Facultad de Medicina, Universidad de Chile, Chile
| | - Víctor Hugo Cornejo
- Department of Neuroscience, Facultad de Medicina, Universidad de Chile, Chile; Biomedical Neuroscience Institute (BNI), Facultad de Medicina, Universidad de Chile, Chile
| | - Andrés Couve
- Department of Neuroscience, Facultad de Medicina, Universidad de Chile, Chile; Biomedical Neuroscience Institute (BNI), Facultad de Medicina, Universidad de Chile, Chile.
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22
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Cioni JM, Koppers M, Holt CE. Molecular control of local translation in axon development and maintenance. Curr Opin Neurobiol 2018; 51:86-94. [PMID: 29549711 DOI: 10.1016/j.conb.2018.02.025] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 02/24/2018] [Accepted: 02/26/2018] [Indexed: 11/27/2022]
Abstract
The tips of axons are often far away from the cell soma where most proteins are synthesized. Recent work has revealed that axonal mRNA transport and localised translation are key regulatory mechanisms that allow these distant outposts of the cell to respond rapidly to extrinsic factors and maintain axonal homeostasis. Here, we review recent evidence pointing to an increasingly broad role for local protein synthesis in controlling axon shape, synaptogenesis and axon survival by regulating diverse cellular processes such as vesicle trafficking, cytoskeletal remodelling and mitochondrial integrity. We further highlight current research on the regulatory mechanisms that coordinate the localization and translation of functionally linked mRNAs in axons.
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Affiliation(s)
- Jean-Michel Cioni
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Max Koppers
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Christine E Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK.
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23
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Mathur C, Johnson KR, Tong BA, Miranda P, Srikumar D, Basilio D, Latorre R, Bezanilla F, Holmgren M. Demonstration of ion channel synthesis by isolated squid giant axon provides functional evidence for localized axonal membrane protein translation. Sci Rep 2018; 8:2207. [PMID: 29396520 PMCID: PMC5797086 DOI: 10.1038/s41598-018-20684-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 01/18/2018] [Indexed: 12/18/2022] Open
Abstract
Local translation of membrane proteins in neuronal subcellular domains like soma, dendrites and axon termini is well-documented. In this study, we isolated the electrical signaling unit of an axon by dissecting giant axons from mature squids (Dosidicus gigas). Axoplasm extracted from these axons was found to contain ribosomal RNAs, ~8000 messenger RNA species, many encoding the translation machinery, membrane proteins, translocon and signal recognition particle (SRP) subunits, endomembrane-associated proteins, and unprecedented proportions of SRP RNA (~68% identical to human homolog). While these components support endoplasmic reticulum-dependent protein synthesis, functional assessment of a newly synthesized membrane protein in axolemma of an isolated axon is technically challenging. Ion channels are ideal proteins for this purpose because their functional dynamics can be directly evaluated by applying voltage clamp across the axon membrane. We delivered in vitro transcribed RNA encoding native or Drosophila voltage-activated Shaker KV channel into excised squid giant axons. We found that total K+ currents increased in both cases; with added inactivation kinetics on those axons injected with RNA encoding the Shaker channel. These results provide unambiguous evidence that isolated axons can exhibit de novo synthesis, assembly and membrane incorporation of fully functional oligomeric membrane proteins.
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Affiliation(s)
- Chhavi Mathur
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Kory R Johnson
- Bioinformatics Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Brian A Tong
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Pablo Miranda
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Deepa Srikumar
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Daniel Basilio
- Facultad de Ciencias, Universidad de Chile, Santiago, 7750000, Chile
| | - Ramon Latorre
- Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, 2366103, Chile.
| | - Francisco Bezanilla
- Department of Biochemistry and Molecular Biology, University of Chicago, Gordon Center for Integrative Sciences, Chicago, Illinois, 60637, USA.
| | - Miguel Holmgren
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, 20892, USA.
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24
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Abstract
Post-transcriptional regulation is linked to the development of pain hypersensitivity. A growing body of evidence indicates that RNA-binding proteins are involved in pain. RNA-based inhibitors are a potential new source of pain therapeutics.
RNA-protein interactions permeate biology. Transcription, translation, processing, and mRNA decay all hinge on widespread use of regulatory information decoded by RNA-binding proteins. The final committed step of protein synthesis, translation, is intimately linked to nociceptor excitability. Understanding the factors that control translation is essential as nociceptor plasticity is a hallmark of persistent pain. Here, we review the growing body of evidence for widespread involvement of RNA-binding proteins in pain. Many of the relevant factors have been implicated in post-transcriptional and translational mechanisms of mRNA control. We propose that recent advances in the development of RNA-based therapeutics provide a potential means to exploit our current understanding of liaisons between RNAs and proteins for therapeutic purposes.
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Affiliation(s)
| | - Zachary T. Campbell
- Corresponding author at: Department of Biological Sciences, 800 W. Campbell Road, RL10 BSB 12.510, Richardson, TX 75080, United States.
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25
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Tóth EN, Lohith A, Mondal M, Guo J, Fukamizu A, Pourmand N. Single-cell nanobiopsy reveals compartmentalization of mRNAs within neuronal cells. J Biol Chem 2018; 293:4940-4951. [PMID: 29378846 DOI: 10.1074/jbc.m117.800763] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 01/21/2018] [Indexed: 12/22/2022] Open
Abstract
In highly polarized cells such as neurons, compartmentalization of mRNA and of local protein synthesis enables remarkably fast, precise, and local responses to external stimuli. These responses are highly important for neuron growth cone guidance, synapse formation, and regeneration following injury. Because an altered spatial distribution of mRNA can result in mental retardation or neurodegenerative diseases, subcellular transcriptome analysis of neurons could be a useful tool for studying these conditions, but current techniques, such as in situ hybridization, bulk microarray, and RNA-Seq, impose tradeoffs between spatial resolution and multiplexing. To obtain a comprehensive analysis of the cell body versus neurite transcriptome from the same neuron, we have recently developed a label-free, single-cell nanobiopsy platform based on scanning ion conductance microscopy that uses electrowetting within a quartz nanopipette to extract cellular material from living cells with minimal disruption of the cellular membrane and milieu. In this study, we used this platform to collect samples from the cell bodies and neurites of human neurons and analyzed the mRNA pool with multiplex RNA sequencing. The minute volume of a nanobiopsy sample allowed us to extract samples from several locations in the same cell and to map the various mRNA species to specific subcellular locations. In addition to previously identified transcripts, we discovered new sets of mRNAs localizing to neurites, including nuclear genes such as Eomes and Hmgb3 In summary, our single-neuron nanobiopsy analysis provides opportunities to improve our understanding of intracellular mRNA transport and local protein composition in neuronal growth, connectivity, and function.
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Affiliation(s)
- Eszter N Tóth
- Ph.D. Program in Human Biology, School of Integrative and Global Majors, Ibaraki 305-8577, Japan; Life Science Center, Tsukuba Advanced Research Alliance, Department of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8577, Japan; Department of Biomolecular Engineering, Jack Baskin School of Engineering, University of California at Santa Cruz, Santa Cruz, California 95064
| | - Akshar Lohith
- Department of Biomolecular Engineering, Jack Baskin School of Engineering, University of California at Santa Cruz, Santa Cruz, California 95064
| | - Manas Mondal
- Department of Chemistry and Biochemistry & Biodesign Institute, Arizona State University, Tempe, Arizona 85287
| | - Jia Guo
- Department of Chemistry and Biochemistry & Biodesign Institute, Arizona State University, Tempe, Arizona 85287
| | - Akiyoshi Fukamizu
- Ph.D. Program in Human Biology, School of Integrative and Global Majors, Ibaraki 305-8577, Japan; Life Science Center, Tsukuba Advanced Research Alliance, Department of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8577, Japan
| | - Nader Pourmand
- Department of Biomolecular Engineering, Jack Baskin School of Engineering, University of California at Santa Cruz, Santa Cruz, California 95064.
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26
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Bellon A, Iyer A, Bridi S, Lee FCY, Ovando-Vázquez C, Corradi E, Longhi S, Roccuzzo M, Strohbuecker S, Naik S, Sarkies P, Miska E, Abreu-Goodger C, Holt CE, Baudet ML. miR-182 Regulates Slit2-Mediated Axon Guidance by Modulating the Local Translation of a Specific mRNA. Cell Rep 2017; 18:1171-1186. [PMID: 28147273 PMCID: PMC5300892 DOI: 10.1016/j.celrep.2016.12.093] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Revised: 12/07/2016] [Accepted: 12/27/2016] [Indexed: 11/15/2022] Open
Abstract
During brain wiring, cue-induced axon behaviors such as directional steering and branching are aided by localized mRNA translation. Different guidance cues elicit translation of subsets of mRNAs that differentially regulate the cytoskeleton, yet little is understood about how specific mRNAs are selected for translation. MicroRNAs (miRNAs) are critical translational regulators that act through a sequence-specific mechanism. Here, we investigate the local role of miRNAs in mRNA-specific translation during pathfinding of Xenopus laevis retinal ganglion cell (RGC) axons. Among a rich repertoire of axonal miRNAs, miR-182 is identified as the most abundant. Loss of miR-182 causes RGC axon targeting defects in vivo and impairs Slit2-induced growth cone (GC) repulsion. We find that miR-182 targets cofilin-1 mRNA, silencing its translation, and Slit2 rapidly relieves the repression without causing miR-182 degradation. Our data support a model whereby miR-182 reversibly gates the selection of transcripts for fast translation depending on the extrinsic cue. Small RNA-seq analysis reveals that miR-182 is the most abundant miRNA in RGC axons miR-182 regulates Slit2-mediated axon guidance of RGCs in vitro and in vivo miR-182 silences cofilin-1 local protein synthesis in growth cones Slit2 rapidly lifts miR-182-mediated repression of cofilin-1 without degrading it
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Affiliation(s)
- Anaïs Bellon
- PDN Department, University of Cambridge, Cambridge CB23DY, UK
| | - Archana Iyer
- CIBIO, University of Trento, Trento 38123, Italy
| | - Simone Bridi
- CIBIO, University of Trento, Trento 38123, Italy
| | - Flora C Y Lee
- PDN Department, University of Cambridge, Cambridge CB23DY, UK
| | | | | | - Sara Longhi
- CIBIO, University of Trento, Trento 38123, Italy
| | | | | | - Sindhu Naik
- CIBIO, University of Trento, Trento 38123, Italy
| | - Peter Sarkies
- Gurdon Institute, University of Cambridge, Cambridge CB21QN, UK
| | - Eric Miska
- Gurdon Institute, University of Cambridge, Cambridge CB21QN, UK
| | - Cei Abreu-Goodger
- Unidad de Genómica Avanzada (Langebio), Cinvestav, Irapuato 36821, Mexico
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27
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Luarte A, Cornejo VH, Bertin F, Gallardo J, Couve A. The axonal endoplasmic reticulum: One organelle-many functions in development, maintenance, and plasticity. Dev Neurobiol 2017; 78:181-208. [PMID: 29134778 DOI: 10.1002/dneu.22560] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 11/02/2017] [Accepted: 11/07/2017] [Indexed: 12/11/2022]
Abstract
The endoplasmic reticulum (ER) is highly conserved in eukaryotes and neurons. Indeed, the localization of the organelle in axons has been known for nearly half a century. However, the relevance of the axonal ER is only beginning to emerge. In this review, we discuss the structure of the ER in axons, examining the role of ER-shaping proteins and highlighting reticulons. We analyze the multiple functions of the ER and their potential contribution to axonal physiology. First, we examine the emerging roles of the axonal ER in lipid synthesis, protein translation, processing, quality control, and secretory trafficking of transmembrane proteins. We also review the impact of the ER on calcium dynamics, focusing on intracellular mechanisms and functions. We describe the interactions between the ER and endosomes, mitochondria, and synaptic vesicles. Finally, we analyze available proteomic data of axonal preparations to reveal the dynamic functionality of the ER in axons during development. We suggest that the dynamic proteome and a validated axonal interactome, together with state-of-the-art methodologies, may provide interesting research avenues in axon physiology that may extend to pathology and regeneration. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 181-208, 2018.
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Affiliation(s)
- Alejandro Luarte
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Víctor Hugo Cornejo
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Francisca Bertin
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Javiera Gallardo
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Andrés Couve
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
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28
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Costa CJ, Willis DE. To the end of the line: Axonal mRNA transport and local translation in health and neurodegenerative disease. Dev Neurobiol 2017; 78:209-220. [PMID: 29115051 DOI: 10.1002/dneu.22555] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 10/20/2017] [Accepted: 11/01/2017] [Indexed: 12/14/2022]
Abstract
Axons and growth cones, by their very nature far removed from the cell body, encounter unique environments and require distinct populations of proteins. It seems only natural, then, that they have developed mechanisms to locally synthesize a host of proteins required to perform their specialized functions. Acceptance of this ability has taken decades; however, there is now consensus that axons do indeed have the capacity for local translation, and that this capacity is even retained into adulthood. Accumulating evidence supports the role of locally synthesized proteins in the proper development, maintenance, and function of neurons, and newly emerging studies also suggest that disruption in this process has implications in a number of neurodevelopmental and neurodegenerative diseases. Here, we briefly review the long history of axonal mRNA localization and local translation, and the role that these locally synthesized proteins play in normal neuronal function. Additionally, we highlight the emerging evidence that dysregulation in these processes contributes to a wide range of pathophysiology, including neuropsychiatric disorders, Alzheimer's, and motor neuron diseases such as spinal muscular atrophy and Amyotrophic Lateral Sclerosis. © 2017 Wiley Periodicals, Inc. Develop. Neurobiol 78: 209-220, 2018.
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Affiliation(s)
| | - Dianna E Willis
- Burke Medical Research Institute, White Plains, New York, 10605.,Brain & Mind Research Institute, Weill Cornell Medicine, New York, New York
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29
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Terenzio M, Schiavo G, Fainzilber M. Compartmentalized Signaling in Neurons: From Cell Biology to Neuroscience. Neuron 2017; 96:667-679. [PMID: 29096079 DOI: 10.1016/j.neuron.2017.10.015] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 09/27/2017] [Accepted: 10/09/2017] [Indexed: 12/18/2022]
Abstract
Neurons are the largest known cells, with complex and highly polarized morphologies. As such, neuronal signaling is highly compartmentalized, requiring sophisticated transfer mechanisms to convey and integrate information within and between sub-neuronal compartments. Here, we survey different modes of compartmentalized signaling in neurons, highlighting examples wherein the fundamental cell biological processes of protein synthesis and degradation, membrane trafficking, and organelle transport are employed to enable the encoding and integration of information, locally and globally within a neuron. Comparisons to other cell types indicate that neurons accentuate widely shared mechanisms, providing invaluable models for the compartmentalization and transfer mechanisms required and used by most eukaryotic cells.
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Affiliation(s)
- Marco Terenzio
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Giampietro Schiavo
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, London WC1N 3BG, UK; Discoveries Centre for Regenerative and Precision Medicine at UCL, London WC1N 3BG, UK; UK Dementia Research Institute at UCL, London WC1E 6BT, UK
| | - Mike Fainzilber
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
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30
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Montesinos ML. Local translation of the Down syndrome cell adhesion molecule (DSCAM) mRNA in the vertebrate central nervous system. J Neurogenet 2017; 31:223-230. [PMID: 29078722 DOI: 10.1080/01677063.2017.1391250] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- María Luz Montesinos
- Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Sevilla, Spain
- Instituto de Biomedicina de Sevilla, IBIS/Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
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31
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Trafficking of Kv2.1 Channels to the Axon Initial Segment by a Novel Nonconventional Secretory Pathway. J Neurosci 2017; 37:11523-11536. [PMID: 29042434 DOI: 10.1523/jneurosci.3510-16.2017] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Revised: 09/09/2017] [Indexed: 02/07/2023] Open
Abstract
Kv2.1 is a major delayed-rectifier voltage-gated potassium channel widely expressed in neurons of the CNS. Kv2.1 localizes in high-density cell-surface clusters in the soma and proximal dendrites as well as in the axon initial segment (AIS). Given the crucial roles of both of these compartments in integrating signal input and then generating output, this localization of Kv2.1 is ideal for regulating the overall excitability of neurons. Here we used fluorescence recovery after photobleaching imaging, mutagenesis, and pharmacological interventions to investigate the molecular mechanisms that control the localization of Kv2.1 in these two different membrane compartments in cultured rat hippocampal neurons of mixed sex. Our data uncover a unique ability of Kv2.1 channels to use two molecularly distinct trafficking pathways to accomplish this. Somatodendritic Kv2.1 channels are targeted by the conventional secretory pathway, whereas axonal Kv2.1 channels are targeted by a nonconventional trafficking pathway independent of the Golgi apparatus. We further identified a new AIS trafficking motif in the C-terminus of Kv2.1, and show that putative phosphorylation sites in this region are critical for the restricted and clustered localization in the AIS. These results indicate that neurons can regulate the expression and clustering of Kv2.1 in different membrane domains independently by using two distinct localization mechanisms, which would allow neurons to precisely control local membrane excitability.SIGNIFICANCE STATEMENT Our study uncovered a novel mechanism that targets the Kv2.1 voltage-gated potassium channel to two distinct trafficking pathways and two distinct subcellular destinations: the somatodendritic plasma membrane and that of the axon initial segment. We also identified a distinct motif, including putative phosphorylation sites, that is important for the AIS localization. This raises the possibility that the destination of a channel protein can be dynamically regulated via changes in post-translational modification, which would impact the excitability of specific membrane compartments.
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32
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Wong HHW, Lin JQ, Ströhl F, Roque CG, Cioni JM, Cagnetta R, Turner-Bridger B, Laine RF, Harris WA, Kaminski CF, Holt CE. RNA Docking and Local Translation Regulate Site-Specific Axon Remodeling In Vivo. Neuron 2017; 95:852-868.e8. [PMID: 28781168 PMCID: PMC5563073 DOI: 10.1016/j.neuron.2017.07.016] [Citation(s) in RCA: 108] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 06/09/2017] [Accepted: 07/14/2017] [Indexed: 12/03/2022]
Abstract
Nascent proteins can be positioned rapidly at precise subcellular locations by local protein synthesis (LPS) to facilitate localized growth responses. Axon arbor architecture, a major determinant of synaptic connectivity, is shaped by localized growth responses, but it is unknown whether LPS influences these responses in vivo. Using high-resolution live imaging, we examined the spatiotemporal dynamics of RNA and LPS in retinal axons during arborization in vivo. Endogenous RNA tracking reveals that RNA granules dock at sites of branch emergence and invade stabilized branches. Live translation reporter analysis reveals that de novo β-actin hotspots colocalize with docked RNA granules at the bases and tips of new branches. Inhibition of axonal β-actin mRNA translation disrupts arbor dynamics primarily by reducing new branch emergence and leads to impoverished terminal arbors. The results demonstrate a requirement for LPS in building arbor complexity and suggest a key role for pre-synaptic LPS in assembling neural circuits. Tracking endogenous RNA shows that RNA docking predicts axon branch emergence in vivo Axon arbor complexity in vivo depends on local protein synthesis Axonal β-actin synthesis regulates branching by increased branch initiation Live imaging reveals de novo synthesis of β-actin hotspots during branch formation
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Affiliation(s)
- Hovy Ho-Wai Wong
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Julie Qiaojin Lin
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Florian Ströhl
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Cláudio Gouveia Roque
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Jean-Michel Cioni
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Roberta Cagnetta
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Benita Turner-Bridger
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Romain F Laine
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - William A Harris
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Clemens F Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Christine E Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK.
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33
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Rajman M, Schratt G. MicroRNAs in neural development: from master regulators to fine-tuners. Development 2017; 144:2310-2322. [DOI: 10.1242/dev.144337] [Citation(s) in RCA: 165] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The proper formation and function of neuronal networks is required for cognition and behavior. Indeed, pathophysiological states that disrupt neuronal networks can lead to neurodevelopmental disorders such as autism, schizophrenia or intellectual disability. It is well-established that transcriptional programs play major roles in neural circuit development. However, in recent years, post-transcriptional control of gene expression has emerged as an additional, and probably equally important, regulatory layer. In particular, it has been shown that microRNAs (miRNAs), an abundant class of small regulatory RNAs, can regulate neuronal circuit development, maturation and function by controlling, for example, local mRNA translation. It is also becoming clear that miRNAs are frequently dysregulated in neurodevelopmental disorders, suggesting a role for miRNAs in the etiology and/or maintenance of neurological disease states. Here, we provide an overview of the most prominent regulatory miRNAs that control neural development, highlighting how they act as ‘master regulators’ or ‘fine-tuners’ of gene expression, depending on context, to influence processes such as cell fate determination, cell migration, neuronal polarization and synapse formation.
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Affiliation(s)
- Marek Rajman
- Biochemisch-Pharmakologisches Centrum, Institut für Physiologische Chemie, Philipps-Universität Marburg, Marburg 35043, Germany
| | - Gerhard Schratt
- Biochemisch-Pharmakologisches Centrum, Institut für Physiologische Chemie, Philipps-Universität Marburg, Marburg 35043, Germany
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34
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Kar AN, Lee SJ, Twiss JL. Expanding Axonal Transcriptome Brings New Functions for Axonally Synthesized Proteins in Health and Disease. Neuroscientist 2017; 24:111-129. [PMID: 28593814 DOI: 10.1177/1073858417712668] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intra-axonal protein synthesis has been shown to play critical roles in both development and repair of axons. Axons provide long-range connectivity in the nervous system, and disruption of their function and/or structure is seen in several neurological diseases and disorders. Axonally synthesized proteins or losses in axonally synthesized proteins contribute to neurodegenerative diseases, neuropathic pain, viral transport, and survival of axons. Increasing sensitivity of RNA detection and quantitation coupled with methods to isolate axons to purity has shown that a surprisingly complex transcriptome exists in axons. This extends across different species, neuronal populations, and physiological conditions. These studies have helped define the repertoire of neuronal mRNAs that can localize into axons and imply previously unrecognized functions for local translation in neurons. Here, we review the current state of transcriptomics studies of isolated axons, contrast axonal mRNA profiles between different neuronal types and growth states, and discuss how mRNA transport into and translation within axons contribute to neurological disorders.
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Affiliation(s)
- Amar N Kar
- 1 Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Seung Joon Lee
- 1 Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Jeffery L Twiss
- 1 Department of Biological Sciences, University of South Carolina, Columbia, SC, USA.,2 Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA
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35
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Rangaraju V, Tom Dieck S, Schuman EM. Local translation in neuronal compartments: how local is local? EMBO Rep 2017; 18:693-711. [PMID: 28404606 DOI: 10.15252/embr.201744045] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/15/2017] [Accepted: 03/15/2017] [Indexed: 12/18/2022] Open
Abstract
Efficient neuronal function depends on the continued modulation of the local neuronal proteome. Local protein synthesis plays a central role in tuning the neuronal proteome at specific neuronal regions. Various aspects of translation such as the localization of translational machinery, spatial spread of the newly translated proteins, and their site of action are carried out in specialized neuronal subcompartments to result in a localized functional outcome. In this review, we focus on the various aspects of these local translation compartments such as size, biochemical and organelle composition, structural boundaries, and temporal dynamics. We also discuss the apparent absence of definitive components of translation in these local compartments and the emerging state-of-the-art tools that could help dissecting these conundrums in greater detail in the future.
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Affiliation(s)
- Vidhya Rangaraju
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany
| | | | - Erin M Schuman
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany
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36
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Cornejo VH, Luarte A, Couve A. Global and local mechanisms sustain axonal proteostasis of transmembrane proteins. Traffic 2017; 18:255-266. [PMID: 28220989 DOI: 10.1111/tra.12472] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 02/02/2017] [Accepted: 02/16/2017] [Indexed: 12/22/2022]
Abstract
The control of neuronal protein homeostasis or proteostasis is tightly regulated both spatially and temporally, assuring accurate and integrated responses to external or intrinsic stimuli. Local or autonomous responses in dendritic and axonal compartments are crucial to sustain function during development, physiology and in response to damage or disease. Axons are responsible for generating and propagating electrical impulses in neurons, and the establishment and maintenance of their molecular composition are subject to extreme constraints exerted by length and size. Proteins that require the secretory pathway, such as receptors, transporters, ion channels or cell adhesion molecules, are fundamental for axonal function, but whether axons regulate their abundance autonomously and how they achieve this is not clear. Evidence supports the role of three complementary mechanisms to maintain proteostasis of these axonal proteins, namely vesicular transport, local translation and trafficking and transfer from supporting cells. Here, we review these mechanisms, their molecular machineries and contribution to neuronal function. We also examine the signaling pathways involved in local translation and their role during development and nerve injury. We discuss the relative contributions of a transport-controlled proteome directed by the soma (global regulation) versus a local-controlled proteome based on local translation or cell transfer (local regulation).
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Affiliation(s)
- Víctor Hugo Cornejo
- Program of Physiology and Biophysics, ICBM, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Universidad de Chile, Santiago, Chile
| | - Alejandro Luarte
- Program of Physiology and Biophysics, ICBM, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Universidad de Chile, Santiago, Chile
| | - Andrés Couve
- Program of Physiology and Biophysics, ICBM, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Universidad de Chile, Santiago, Chile
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37
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Neural Progenitor Cells Promote Axonal Growth and Alter Axonal mRNA Localization in Adult Neurons. eNeuro 2017; 4:eN-NWR-0171-16. [PMID: 28197547 PMCID: PMC5291088 DOI: 10.1523/eneuro.0171-16.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Revised: 01/13/2017] [Accepted: 01/13/2017] [Indexed: 01/16/2023] Open
Abstract
The inhibitory environment of the spinal cord and the intrinsic properties of neurons prevent regeneration of axons following CNS injury. However, both ascending and descending axons of the injured spinal cord have been shown to regenerate into grafts of embryonic neural progenitor cells (NPCs). Previous studies have shown that grafts composed of glial-restricted progenitors (GRPs) and neural-restricted progenitors (NRPs) can provide a permissive microenvironment for axon growth. We have used cocultures of adult rat dorsal root ganglion (DRG) neurons together with NPCs, which have shown significant enhancement of axon growth by embryonic rat GRP and GRPs/NRPs, both in coculture conditions and when DRGs are exposed to conditioned medium from the NPC cultures. This growth-promoting effect of NPC-conditioned medium was also seen in injury-conditioned neurons. DRGs cocultured with GRPs/NRPs showed altered expression of regeneration-associated genes at transcriptional and post-transcriptional levels. We found that levels of GAP-43 mRNA increased in DRG cell bodies and axons. However, hepcidin antimicrobial peptide (HAMP) mRNA decreased in the cell bodies of DRGs cocultured with GRPs/NRPs, which is distinct from the increase in cell body HAMP mRNA levels seen in DRGs after injury conditioning. Endogenous GAP-43 and β-actin mRNAs as well as reporter RNAs carrying axonally localizing 3'UTRs of these transcripts showed significantly increased levels in distal axons in the DRGs cocultured with GRPs/NRPs. These results indicate that axon growth promoted by NPCs is associated not only with enhanced transcription of growth-associated genes but also can increase localization of some mRNAs into growing axons.
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38
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Sonic Hedgehog Guides Axons via Zipcode Binding Protein 1-Mediated Local Translation. J Neurosci 2017; 37:1685-1695. [PMID: 28073938 DOI: 10.1523/jneurosci.3016-16.2016] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 12/15/2016] [Accepted: 12/27/2016] [Indexed: 01/27/2023] Open
Abstract
Sonic hedgehog (Shh) attracts spinal cord commissural axons toward the floorplate. How Shh elicits changes in the growth cone cytoskeleton that drive growth cone turning is unknown. We find that the turning of rat commissural axons up a Shh gradient requires protein synthesis. In particular, Shh stimulation increases β-actin protein at the growth cone even when the cell bodies have been removed. Therefore, Shh induces the local translation of β-actin at the growth cone. We hypothesized that this requires zipcode binding protein 1 (ZBP1), an mRNA-binding protein that transports β-actin mRNA and releases it for local translation upon phosphorylation. We found that Shh stimulation increases phospho-ZBP1 levels in the growth cone. Disruption of ZBP1 phosphorylation in vitro abolished the turning of commissural axons toward a Shh gradient. Disruption of ZBP1 function in vivo in mouse and chick resulted in commissural axon guidance errors. Therefore, ZBP1 is required for Shh to guide commissural axons. This identifies ZBP1 as a new mediator of noncanonical Shh signaling in axon guidance.SIGNIFICANCE STATEMENT Sonic hedgehog (Shh) guides axons via a noncanonical signaling pathway that is distinct from the canonical Hedgehog signaling pathway that specifies cell fate and morphogenesis. Axon guidance is driven by changes in the growth cone in response to gradients of guidance molecules. Little is known about the molecular mechanism of how Shh orchestrates changes in the growth cone cytoskeleton that are required for growth cone turning. Here, we show that the guidance of axons by Shh requires protein synthesis. Zipcode binding protein 1 (ZBP1) is an mRNA-binding protein that regulates the local translation of proteins, including actin, in the growth cone. We demonstrate that ZBP1 is required for Shh-mediated axon guidance, identifying a new member of the noncanonical Shh signaling pathway.
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39
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Abstract
Although tctp expression in many areas of the human brain was reported more than 15 years ago, little was known about how it functions in neurons. The early notion that Tctp is primarily expressed in mitotic cells, together with reports suggesting a relative low abundance in the brain, has perhaps potentiated this almost complete disregard for the study of Tctp in the context of neuron biology. However, recent evidence has challenged this view, as a number of independent genome-wide profiling studies identified tctp mRNA among the most enriched in the axonal compartment across diverse neuronal populations, including embryonic retinal ganglion cells. Considering the emerging parallels between axon guidance and cancer cell invasion, the axonal expression of cancer-associated tctp was suggestive of it holding an unexplored role in the wiring of neuronal circuits. Our study revealed that Tctp is necessary for the accurate and timely development of axon projections during the formation of vertebrate retinal circuits via its association with the survival machinery of the axon. Globally, the findings indicate that compromised pro-survival signaling in Tctp-deficient axons results in mitochondrial dysfunction and a subsequent decrease in axonal mitochondrial density. These effects likely translate into a metabolic state inadequate to support the normal guidance and extension processes of a developing axon.
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Affiliation(s)
- Cláudio Gouveia Roque
- The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, USA.
| | - Christine E Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, England, UK
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40
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López-Leal R, Alvarez J, Court FA. Origin of axonal proteins: Is the axon-schwann cell unit a functional syncytium? Cytoskeleton (Hoboken) 2016; 73:629-639. [DOI: 10.1002/cm.21319] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 07/28/2016] [Accepted: 08/02/2016] [Indexed: 12/31/2022]
Affiliation(s)
- Rodrigo López-Leal
- Faculty of Sciences, Center for Integrative Biology; Universidad Mayor; Santiago Chile
- Geroscience Center for Brain Health and Metabolism; Santiago Chile
- Millenium Nucleus for Regenerative Biology; Santiago Chile
| | - Jaime Alvarez
- Faculty of Sciences, Center for Integrative Biology; Universidad Mayor; Santiago Chile
- Millenium Nucleus for Regenerative Biology; Santiago Chile
| | - Felipe A. Court
- Faculty of Sciences, Center for Integrative Biology; Universidad Mayor; Santiago Chile
- Geroscience Center for Brain Health and Metabolism; Santiago Chile
- Millenium Nucleus for Regenerative Biology; Santiago Chile
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41
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Preitner N, Quan J, Li X, Nielsen FC, Flanagan JG. IMP2 axonal localization, RNA interactome, and function in the development of axon trajectories. Development 2016; 143:2753-9. [PMID: 27385015 DOI: 10.1242/dev.128348] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 06/13/2016] [Indexed: 01/28/2023]
Abstract
RNA-based regulatory mechanisms play important roles in the development and plasticity of neural circuits and neurological disease. Developing axons provide a model well suited to the study of RNA-based regulation, and contain specific subsets of mRNAs that are locally translated and have roles in axon pathfinding. However, the RNA-binding proteins involved in axon pathfinding, and their corresponding mRNA targets, are still largely unknown. Here we find that the RNA-binding protein IMP2 (Igf2bp2) is strikingly enriched in developing axon tracts, including in spinal commissural axons. We used the HITS-CLIP approach to perform a genome-wide identification of RNAs that interact directly with IMP2 in the native context of developing mouse brain. This IMP2 interactome was highly enriched for mRNA targets related to axon guidance. Accordingly, IMP2 knockdown in the developing spinal cord led to strong defects in commissural axon trajectories at the midline intermediate target. These results reveal a highly distinctive axonal enrichment of IMP2, show that it interacts with a network of axon guidance-related mRNAs, and reveal that it is required for normal axon pathfinding during vertebrate development.
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Affiliation(s)
- Nicolas Preitner
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
| | - Jie Quan
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
| | - Xinmin Li
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
| | - Finn C Nielsen
- Center for Genomic Medicine, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, Copenhagen Ø DK-2100, Denmark
| | - John G Flanagan
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
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42
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Affiliation(s)
- Shruti Jain
- Department of Biological Sciences, Kent State University, Kent, OH, USA
| | - Kristy Welshhans
- Department of Biological Sciences, Kent State University, Kent, OH, USA; School of Biomedical Sciences, Kent State University, Kent, OH, USA
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43
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Wang W, Rai A, Hur EM, Smilansky Z, Chang KT, Min KT. DSCR1 is required for both axonal growth cone extension and steering. J Cell Biol 2016; 213:451-62. [PMID: 27185837 PMCID: PMC4878092 DOI: 10.1083/jcb.201510107] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 04/22/2016] [Indexed: 11/26/2022] Open
Abstract
Wang et al. identify that DSCR1, a gene on chromosome 21 that is associated with Down syndrome, controls both the rate and direction of axon growth in response to extrinsic cues by regulating cytoskeletal dynamics and local protein synthesis in the growth cone. Local information processing in the growth cone is essential for correct wiring of the nervous system. As an axon navigates through the developing nervous system, the growth cone responds to extrinsic guidance cues by coordinating axon outgrowth with growth cone steering. It has become increasingly clear that axon extension requires proper actin polymerization dynamics, whereas growth cone steering involves local protein synthesis. However, molecular components integrating these two processes have not been identified. Here, we show that Down syndrome critical region 1 protein (DSCR1) controls axon outgrowth by modulating growth cone actin dynamics through regulation of cofilin activity (phospho/dephospho-cofilin). Additionally, DSCR1 mediates brain-derived neurotrophic factor–induced local protein synthesis and growth cone turning. Our study identifies DSCR1 as a key protein that couples axon growth and pathfinding by dually regulating actin dynamics and local protein synthesis.
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Affiliation(s)
- Wei Wang
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Asit Rai
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Eun-Mi Hur
- Brain Science Institute-Center for Neuroscience, Korea Institute of Science and Technology, Seoul 02792, Korea Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Korea Institute of Science and Technology, Seoul 02792, Korea Department of Neuroscience, University of Science and Technology, Daejeon 34113, Korea
| | | | - Karen T Chang
- Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA 90089 Department of Cell and Neurobiology, University of Southern California, Los Angeles, CA 90089
| | - Kyung-Tai Min
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
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44
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Yan X, Hoek TA, Vale RD, Tanenbaum ME. Dynamics of Translation of Single mRNA Molecules In Vivo. Cell 2016; 165:976-89. [PMID: 27153498 PMCID: PMC4889334 DOI: 10.1016/j.cell.2016.04.034] [Citation(s) in RCA: 311] [Impact Index Per Article: 38.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 04/04/2016] [Accepted: 04/11/2016] [Indexed: 11/16/2022]
Abstract
Regulation of mRNA translation, the process by which ribosomes decode mRNAs into polypeptides, is used to tune cellular protein levels. Currently, methods for observing the complete process of translation from single mRNAs in vivo are unavailable. Here, we report the long-term (>1 hr) imaging of single mRNAs undergoing hundreds of rounds of translation in live cells, enabling quantitative measurements of ribosome initiation, elongation, and stalling. This approach reveals a surprising heterogeneity in the translation of individual mRNAs within the same cell, including rapid and reversible transitions between a translating and non-translating state. Applying this method to the cell-cycle gene Emi1, we find strong overall repression of translation initiation by specific 5' UTR sequences, but individual mRNA molecules in the same cell can exhibit dramatically different translational efficiencies. The ability to observe translation of single mRNA molecules in live cells provides a powerful tool to study translation regulation.
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Affiliation(s)
- Xiaowei Yan
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158-2517, USA
| | - Tim A Hoek
- Hubrecht Institute, The Royal Netherlands Academy of Arts and Sciences (KNAW) and University Medical Center Utrecht, Utrecht 3584CT, the Netherlands
| | - Ronald D Vale
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158-2517, USA
| | - Marvin E Tanenbaum
- Hubrecht Institute, The Royal Netherlands Academy of Arts and Sciences (KNAW) and University Medical Center Utrecht, Utrecht 3584CT, the Netherlands.
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45
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Intra-axonal protein synthesis in development and beyond. Int J Dev Neurosci 2016; 55:140-149. [PMID: 26970010 DOI: 10.1016/j.ijdevneu.2016.03.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 03/03/2016] [Accepted: 03/07/2016] [Indexed: 12/15/2022] Open
Abstract
Proteins can be locally produced in the periphery of a cell, allowing a rapid and spatially precise response to the changes in its environment. This process is especially relevant in highly polarized and morphologically complex cells such as neurons. The study of local translation in axons has evolved from being primarily focused on developing axons, to the notion that also mature axons can produce proteins. Axonal translation has been implied in several physiological and pathological conditions, and in all cases it shares common molecular actors and pathways as well as regulatory mechanisms. Here, we review the main findings in these fields, and attempt to highlight shared principles.
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46
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Axons provide the secretory machinery for trafficking of voltage-gated sodium channels in peripheral nerve. Proc Natl Acad Sci U S A 2016; 113:1823-8. [PMID: 26839409 DOI: 10.1073/pnas.1514943113] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
The regulation of the axonal proteome is key to generate and maintain neural function. Fast and slow axoplasmic waves have been known for decades, but alternative mechanisms to control the abundance of axonal proteins based on local synthesis have also been identified. The presence of the endoplasmic reticulum has been documented in peripheral axons, but it is still unknown whether this localized organelle participates in the delivery of axonal membrane proteins. Voltage-gated sodium channels are responsible for action potentials and are mostly concentrated in the axon initial segment and nodes of Ranvier. Despite their fundamental role, little is known about the intracellular trafficking mechanisms that govern their availability in mature axons. Here we describe the secretory machinery in axons and its contribution to plasma membrane delivery of sodium channels. The distribution of axonal secretory components was evaluated in axons of the sciatic nerve and in spinal nerve axons after in vivo electroporation. Intracellular protein trafficking was pharmacologically blocked in vivo and in vitro. Axonal voltage-gated sodium channel mRNA and local trafficking were examined by RT-PCR and a retention-release methodology. We demonstrate that mature axons contain components of the endoplasmic reticulum and other biosynthetic organelles. Axonal organelles and sodium channel localization are sensitive to local blockade of the endoplasmic reticulum to Golgi transport. More importantly, secretory organelles are capable of delivering sodium channels to the plasma membrane in isolated axons, demonstrating an intrinsic capacity of the axonal biosynthetic route in regulating the axonal proteome in mammalian axons.
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Jain S, Welshhans K. Netrin-1 induces local translation of down syndrome cell adhesion molecule in axonal growth cones. Dev Neurobiol 2015; 76:799-816. [PMID: 26518186 DOI: 10.1002/dneu.22360] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 10/14/2015] [Accepted: 10/28/2015] [Indexed: 01/16/2023]
Abstract
Down syndrome cell adhesion molecule (DSCAM) plays an important role in many neurodevelopmental processes such as axon guidance, dendrite arborization, and synapse formation. DSCAM is located in the Down syndrome trisomic region of human chromosome 21 and may contribute to the Down syndrome brain phenotype, which includes a reduction in the formation of long-distance connectivity. The local translation of a select group of mRNA transcripts within growth cones is necessary for the formation of appropriate neuronal connectivity. Interestingly, we have found that Dscam mRNA is localized to growth cones of mouse hippocampal neurons, and is dynamically regulated in response to the axon guidance molecule, netrin-1. Furthermore, netrin-1 stimulation results in an increase in locally translated DSCAM protein in growth cones. Deleted in colorectal cancer (DCC), a netrin-1 receptor, is required for the netrin-1-induced increase in Dscam mRNA local translation. We also find that two RNA-binding proteins-fragile X mental retardation protein (FMRP) and cytoplasmic polyadenylation element binding protein (CPEB)-colocalize with Dscam mRNA in growth cones, suggesting their regulation of Dscam mRNA localization and translation. Finally, overexpression of DSCAM in mouse cortical neurons results in a severe stunting of axon outgrowth and branching, suggesting that an increase in DSCAM protein results in a structural change having functional consequences. Taken together, these results suggest that netrin-1-induced local translation of Dscam mRNA during embryonic development may be an important mechanism to regulate axon growth and guidance in the developing nervous system. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 799-816, 2016.
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Affiliation(s)
- Shruti Jain
- Department of Biological Sciences, Kent State University, Kent, Ohio, 44242
| | - Kristy Welshhans
- Department of Biological Sciences, Kent State University, Kent, Ohio, 44242.,School of Biomedical Sciences, Kent State University, Kent, Ohio, 44242
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48
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Hsu WL, Chung HW, Wu CY, Wu HI, Lee YT, Chen EC, Fang W, Chang YC. Glutamate Stimulates Local Protein Synthesis in the Axons of Rat Cortical Neurons by Activating α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid (AMPA) Receptors and Metabotropic Glutamate Receptors. J Biol Chem 2015; 290:20748-20760. [PMID: 26134564 DOI: 10.1074/jbc.m115.638023] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Indexed: 12/20/2022] Open
Abstract
Glutamate is the principal excitatory neurotransmitter in the mammalian CNS. By analyzing the metabolic incorporation of azidohomoalanine, a methionine analogue, in newly synthesized proteins, we find that glutamate treatments up-regulate protein translation not only in intact rat cortical neurons in culture but also in the axons emitting from cortical neurons before making synapses with target cells. The process by which glutamate stimulates local translation in axons begins with the binding of glutamate to the ionotropic AMPA receptors and metabotropic glutamate receptor 1 and members of group 2 metabotropic glutamate receptors on the plasma membrane. Subsequently, the activated mammalian target of rapamycin (mTOR) signaling pathway and the rise in Ca(2+), resulting from Ca(2+) influxes through calcium-permeable AMPA receptors, voltage-gated Ca(2+) channels, and transient receptor potential canonical channels, in axons stimulate the local translation machinery. For comparison, the enhancement effects of brain-derived neurotrophic factor (BDNF) on the local protein synthesis in cortical axons were also studied. The results indicate that Ca(2+) influxes via transient receptor potential canonical channels and activated the mTOR pathway in axons also mediate BDNF stimulation to local protein synthesis. However, glutamate- and BDNF-induced enhancements of translation in axons exhibit different kinetics. Moreover, Ca(2+) and mTOR signaling appear to play roles carrying different weights, respectively, in transducing glutamate- and BDNF-induced enhancements of axonal translation. Thus, our results indicate that exposure to transient increases of glutamate and more lasting increases of BDNF would stimulate local protein synthesis in migrating axons en route to their targets in the developing brain.
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Affiliation(s)
- Wei-Lun Hsu
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Hui-Wen Chung
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Chih-Yueh Wu
- Institute of Systems Neuroscience, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Huei-Ing Wu
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Yu-Tao Lee
- Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan
| | - En-Chan Chen
- Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Weilun Fang
- Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Yen-Chung Chang
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu 300, Taiwan; Institute of Systems Neuroscience, National Tsing Hua University, Hsinchu 300, Taiwan; Institute of Nanoengineering and Microsystems, National Tsing Hua University, Hsinchu 300, Taiwan.
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49
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Baleriola J, Jean Y, Troy C, Hengst U. Detection of Axonally Localized mRNAs in Brain Sections Using High-Resolution In Situ Hybridization. J Vis Exp 2015:e52799. [PMID: 26131922 DOI: 10.3791/52799] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
mRNAs are frequently localized to vertebrate axons and their local translation is required for axon pathfinding or branching during development and for maintenance, repair or neurodegeneration in postdevelopmental periods. High throughput analyses have recently revealed that axons have a more dynamic and complex transcriptome than previously expected. These analysis, however have been mostly done in cultured neurons where axons can be isolated from the somato-dendritic compartments. It is virtually impossible to achieve such isolation in whole tissues in vivo. Thus, in order to verify the recruitment of mRNAs and their functional relevance in a whole animal, transcriptome analyses should ideally be combined with techniques that allow the visualization of mRNAs in situ. Recently, novel ISH technologies that detect RNAs at a single-molecule level have been developed. This is especially important when analyzing the subcellular localization of mRNA, since localized RNAs are typically found at low levels. Here we describe two protocols for the detection of axonally-localized mRNAs using a novel ultrasensitive RNA ISH technology. We have combined RNAscope ISH with axonal counterstain using fluorescence immunohistochemistry or histological dyes to verify the recruitment of Atf4 mRNA to axons in vivo in the mature mouse and human brains.
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Affiliation(s)
| | - Ying Jean
- College of Physicians and Surgeons, Columbia University
| | - Carol Troy
- College of Physicians and Surgeons, Columbia University
| | - Ulrich Hengst
- College of Physicians and Surgeons, Columbia University;
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50
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Abstract
Signaling classically involves the secretion of diverse molecules that bind specific cell-surface receptors and engage intracellular transduction cascades. Some exceptions-namely, lipophilic agents-can cross plasma membranes to bind intracellular receptors and be carried to the nucleus to regulate transcription. Homeoprotein transcription factors are among the few proteins with such a capacity. Here, we review the signaling activities of homeoproteins in the developing and adult nervous system, with particular emphasis on axon/cell migration and postnatal critical periods of cerebral cortex plasticity. We also describe homeoprotein non-cell-autonomous mechanisms and explore how this "novel" signaling pathway impacts emerging research in brain development and physiology. In this context, we explore hypotheses on the evolution of signaling, the role of homeoproteins as early morphogens, and their therapeutic potential for neurological and psychiatric diseases.
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